Ignition system for propellants



April 9, 1963 w. F. KAUFMANN, JR., ETAL 3,084,601

IGNITION SYSTEM FOR PROPELLANTS Filed March 1'7, 1961 2 Sheets-Sheet 1 INVENTORS WILLIAM F. KAUFMANN, JR. HENRY S. LIPINSKI a. a. 5 MW ATTORNEYS A ril 9, 1963 w. F. KAUFMANN, JR., ETAL 3,084,601

IGNITION SYSTEM FOR PROPELLANTS Filed March 17, 1961 2 Sheets-Sheet 2 atent 3,084,601 Patented Apr. 9, 1953 3,084,601 IGNITIQN SYSTEM FOR PRQPELLANTS William F. Kaufmann, 3n, and Henry S. Lipinslri, Ph ladelphia, Pa, assignors to the United States of America as represented by the Secretary of the Army Filed Mar. 17, 1961, Ser. No. 96,618 4 Claims. ((Il. 89-4.?) (Granted under Title 35, US. Code (1952), sec. 266) The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment to us of any royalty thereon.

This invention relates to caseless ammunition in recoilless guns and to ignition of the primer for such rounds. An object is to reduce the danger of misfires and to simplify the construction in such guns and ammunition by insuring the critical clearances needed without the high production costs heretofore necessary to obtain the tolerances permissible in obtaining such clearances.

In fixed ammunition using metal cartridge cases there is usually a base flange accurately locating the round in the gun for firing by use of a percussion primer. With the so called caseless rounds using a consumable case or covering for the propellant there is usually no such base locating flange with the result the needed clearance between the firing pin and the ammunition has been troublesome to maintain.

According to this invention this difiiculty has been avoided. Specifically, a primer holder is made slidable within a round and a breech closure caused to impinge upon such a holder in closing the breech with the result a needed critical clearance for the firing pin may be more readily obtained.

In the drawing FIG. 1 is a longitudinal section with parts broken away through a gun and ammunition of the type named.

FIG. 2 is a longitudinal section through a part of the breech closure and rear end portion of a round in position for firing.

FIG. 3 is a left end view of the gun of FIG. 1 without ammunition.

A conventional recoilless gun with a generally central venturi is provided to receive fixed ammunition of the type having a projectile 12, a rotating band 13, stabilizing fins 14, and a propelling charge between the projectile and fins. The gun is provided with the central venturi opening 16 closed by a bar type breech 17 to hold the round therein. As shown in FIGS. 1 and 3 the bar breech is pivotally mounted at 18. A hinge bar 18a between the bar closure 17 and pivot 18 when open supports the bar closure 17 rotatably supported on a central plug 18b fixed to the hinge bar 18a. A handle 180 is fixed to the bar breech 17 for rotation between the stops 19 and '20 fixed to the gun to enable the bar breech to be locked in closed position by an interrupted thread 21 as is customary. Within the bar breech '17 is a firing pin 22 to be actuated in the usual manner for firing a percussion primer. The foregoing combination is not new apart from this improvement.

As shown in FIG. 2 a primer insert 23 is threaded into the central bar or boom carrying the propellant 15. Also threaded into the insert 23 at its forward end is a front end plate 24 having an axial perforation through which the primer flame passes for ignition of the propellant. Slidable within the insert 23 is a two part unit consisting of a plug holder 25 and a primer housing 26 threaded together as shown for translation between an abutment 27 at one end and a radially inwardly extending flange 27a on the front end plate 24. A spring 28 in cooperation with plate 24 and with the plug holder 25 biases the holder 25 to its position against abutment 27. Frictionally held within the holder 25 is a firing plug 29 adapted to be impinged by firing pin 22 and forced against the percussion primer cup 30 for igniting the primer material in cup 36 and directing the primer flame from cup 30* forwardly into the black powder 31 for directing a still larger priming flame forwardly into the propellant charge for igniting the same, or the flame from powder 31 may fire a longer extending quantity of black powder within the boom 33 supporting the propellant material as has been done heretofore.

The distance between the end of the firing pin 22 and whatever it impinges upon is known to be fairly critical and should be between about .015 inch and .020 inch. Also the distance between a firing plug 29 and a primer cup 30 should be about .001 inch and .002 inch. Heretofore the number of threaded or other connections between the projectile and rear end of the fins 14- has been large enough to make it troublesome to keep all these clearances within the values they should have. That is why the present invention was devised to make this goal easier to attain.

Now the bar breech 17 on being closed engages to rear face of plug holder 25 compressing spring 28 without affecting these two critical distances mentioned. For the sake of clarity the distance between the end of pin 22 and the rear face of firing plug 29 is shown larger than it actually is. Thus the present invention enables this distance 34 to be readily maintained of a size desired to insure best results with the firing pin 22.

We claim:

1. In a recoilless gun for reception of a caseless round of fixed ammunition and having a generally axial venturi passageway in a rear portion of said gun, the combination therewith of the improvement whereby a primer charge carried by said round may be fired without the necessity for making any connections thereto and whereby the necessity for maintaining critical tolerances between a rotating band on said round and a rear surface of said primer may be preserved, said improvement including a breech bar extending across said venturi passageway and carrying a primer firing pin, a primer holder or container movable longitudinally within said round, a spring cooperating with said container and round for biasing said container rearwardly for engagement with said breech bar on closing the same in its firing position.

2. A gun according to claim 1 in which said primer container is in two parts one of which contains a slidable firing plug and the other of which contains a two part primer namely a percussion primer cup responsive to movement of said firing pin and a main body of said primer for firing said caseless round.

3. In combination with a recoilless rifle comprising a barrel; a chamber in the rear of said barrel having the form of a venturi passageway and adapted to receive a round of fixed ammunition including a projectile having a rearwardly extending, coaxially aligned, tubular boom a caseless propellant charge, and primer means; and a breech closure containing a firing pin and adapted to lock said round within said chamber in such manner that said firing pin is coaxially aligned with said boom, the improvement comprising a primer insert housing mounted in the rear of said boom wherein said primer means is slidably inserted, said primer means being restricted in translatory movement by forward and rearward stops, a spring cooperating With said housing and biasing said primer means against said rearward stop, said rearward stop being located in such position that said breech closure contacts said primer means and compresses said spring at least to some extent when said round is locked within said chamber, whereby the distance between the forward end of said firing pin and the rearward end of said primer means is maintained within limits critical for the obtention of an effective fire signal.

4. The improvement in combination with a recoilless rifle according to claim 3 wherein said boom supports a plurality of fins and said propellant charge is located largely longitudinally between said fins and a main body portion of said projectile.

References Cited in the file of this patent UNITED STATES PATENTS 

3. IN COMBINATION WITH A RECOILLESS RIFLE COMPRISING A BARREL; A CHAMBER IN THE REAR OF SAID BARREL HAVING THE FORM OF A VENTURI PASSAGEWAY AND ADAPTED TO RECEIVE A ROUND OF FIXED AMMUNITION INCLUDING A PROJECTILE HAVING A REARWARDLY EXTENDING, COAXIALLY ALIGNED, TUBULAR BOOM A CASELESS PROPELLANT CHARGE, AND PRIMER MEANS; AND A BREECH CLOSURE CONTAINING A FIRING PIN AND ADAPTED TO LOCK SAID ROUND WITHIN SAID CHAMBER IN SUCH MANNER THAT SAID FIRING PIN IS COAXIALLY ALIGNED WITH SAID BOOM, THE IMPROVEMENT COMPRISING A PRIMER INSERT HOUSING MOUNTED IN THE REAR OF SAID BOOM WHEREIN SAID PRIMER MEANS IS SLIDABLY INSERTED, SAID PRIMER MEANS BEING RESTRICTED IN TRANSLATORY MOVEMENT BY FORWARD AND REARWARD STOPS, A SPRING COOPERATING WITH SAID HOUSING AND BIASING SAID PRIMER MEANS AGAINST SAID REARWARD STOP, SAID REARWARD STOP BEING LOCATED IN SUCH POSITION THAT SAID BREECH CLOSURE CONTACTS SAID PRIMER MEANS AND COMPRESSES SAID SPRING AT LEAST TO SOME EXTENT WHEN SAID ROUND IS LOCKED WITHIN 